Natural-resin photographic medium and process



mama June v1.192s.

. UNITED, STATES 1,581,211 PATENT OFFICE.

MURRAY C. BEEBE AND ALEXANDER MURRAY, CINCINNATI, OHIO, ASSIGHOBS TO THE WADSWOR'I'E WATCH CASE COMPANY, 01' DAYTON, KENTUCKY, A CORPORA- T1011 OF KENTUCKY. I

Io Drawing.

The present invention relates to a photographic medium and rocess employing a natural resin, preferab y a selected asphalturn, as the main base for the photographic 5 medium. The invention or discovery comprises the features and steps hereinafter more fully described and claimed.

The primary purpose of the invention is to provide a sensitized medium in which the main base is a natural resin, preferably asphaltum, bitumen, or the like. A further ob ect is to provide a sensitized asphaltum medium for "photographic purposes which will print rapidly 1n a photographic oper- 16 ation which we work with marked uniformity, which can be readil compounded and applied, and which provi es a thorou l1- lypracticable medium'and process, availa le forallkinds' of photographic purposes, etch- 20 mg, hthographLetc; a

" xain es are" hereinafter given which will ena le the'invention to be understood and racticed. i

O the natural resins, it is preferred to employ the more-sensitive parts of com mercial asphaltum. It notnecessary to describe' the preliminary steps forseparatin'g-the more sensitive parts of xcommercial asphaltum by 80 meansof ether,,-fzetc., as this procedure is well known, zbein fully described in existin literature,= ehave increased thesensit1vity' jof;asphaltum to a. practical every day uniformity; haveremovedthe chemi- 88 cal complexitythathas heretofore been associated with asphaltum developmentsand have made our process applicable to the various demands-ofall the industries which rerbuire a multiplicationof illustrations. 0 ur process makes POSSIbIQ thB production of printing surfaces from continuous tone negatives without recourse to an aquatint grain reticulation, screens, etc. It also inclu es advanced developing steps, all of which-insure great-uniformity inractical results without being Ii mitedto a solutely exact-exposures, It brmgs about an accurate reproduction of the tonal gradation and detail of the ori al and an ease and simplicityof manipu ation which have not been reached heretofore. It is especially available for all'lithographic urposesand is found to cooperate-very wel with screenless litho-processes. There is an advanta NATURAL-RESIN rnoroeaarnrc unnnm m rmcnss.

' A ncaaan m iiovembcr a7, 1922. Serial in. 608,718.

geous. control factor in developing and they process is also available for the production of relief and intaglio printing plates, being of service in all the arts for contact exposures or optical projection. usual arc-lamp source of illumination'found in process engraving establishments the ex- Under the posures may ran e from one-half minute to five minutes at t e outside.

The sensiti'zerfor asphaltum which we Such a coating is flowed or otherwise,applied to a grained or any desired smooth surface, allowed to drain and dry. The cqated'surface is then exposed to a luminous image by contact or by optical projection for from one-half'minute to four minutes according to the character of the image. After the exposure the print is developed with Per cent.

Oleic acid"; 50 White mineral oil.. 50

by applying the same in a gentle. manner and rub g softl with any suitable medium. When comp etely developed the print is rinsed with dilute ammonia and then with water. As heretofore stated, we do notlimit ourselves to these specific formulas, materials,

or; procedure exemplified for the process is susceptible of wirevariation, without sacrificingits great rapidity, to meet theexigencies of almost unlimited demands for speedy and simple reproduction of illus-' trations in the fieldof the graphic arts. In specially referring to asphaltum,"we do not exclude, but definitely include all classes of substances,known as natural resgood results.

ins, etc., with which oursensitizer will cooperate to produce a highly sensitive actinic medium. Additional exam les' of natural resin which may be employe are gum kauri, rubber, manila, congo, gutta percha, rosin, zanzibar, co a1, etc. These materials may be used in t e same manner as asphaltum, and in the proportions stated with respect to asphaltum. While the use of asphaltum is preferred, gum kauri and rubber give The other examplesv listed ive fair results, but, as stated, asphaltum is preferred;

We have also found that the use of iodine, heretofore proposed produces an unstable sensitizer. To be practical the iodine compounds, such as iodoform and a diluting neutral solvent, must not seriously affect the asphaltum while stored in the dark, they must be freely soluble in the asphaltum, percontra, they must rapidly cause the asphaltum to becomeinsoluble under the action of light, and finally, theunacted upon parts must be readily removed by a developing solvent. Our sensitizer is stabilized by adding a small amount of ammonia. Halogen compounds or halides other than iodoform which do not react in the dark but are halo gen liberating under the action of light so as to produce insoluble compounds, are obviously included in our process.

Hydriodic acid and iodoform combined with asphaltum produce a highly sensitive coating. To this may be added a small amount of ammonia which tends to stabilize the coating, or varnish. Before using the varnish, the ammonia preferably is neutralized. The composition may comprise: Hy-

. driodic acid, 10%; ,iodoform, 20%; asphaltum, 79%; ammonia, a small amount.

Colloidal sensitizers, such as the following, in some instances, produce great sensitivity and result in markedly shortening exposures to as short a time as ten seconds. These are exemplified by the following: 4.2 gms. lead triethyl iodide in 30cc. benzene; 3.0 gms. asphaltum' in 15 cc. solvent naphtha, and 3.0 gms. iodoform in 20 cc. ethyl methyl ketone. Such a sensitizer is also very stable making possible its storage for a day without practical deterioration in contrast to unstable sensitizers, which often, spoil ina few hours. Reversals may be produced by using developing solvents that only act on the parts which have been exposed to the light in any desired manner.

' Our process, as already stated is applicable to a multitude of uses, among them we may further specifically mention the production of screenless grained litho-plates; for line en raving on zinc, copper, etc., for relief printing; for half-tone purposes, such as monochrome or color separation plates; intaglio uses like photo and roto-gravure in one or more colors, etc, etc. a

tion printing, by inference, being restricted to same size subjects. We do not confine ourselves to such limitations but include all kinds of enlargements needed in lithographic or other poster work, from half-tone or continuous tone negatives, etc. The treated and selected asphaltum which we use is of itself very slightly sensitive to light, but as stated it is not suificiently sensitive alone to serve any practical ,purposes.

In addition to our finding that iodine produces an unstable sensitizer we have also found that the use of iodine heretofore .proposed as a sensitizer, cannot be accurately so classed because its action is to merely render the asphaltum less soluble. To become practical as a sensitizer iodine must be used in a combined form, from which, through the action of light, iodine will be liberated from the iodine compounds such as iodoform etc.

What we claim is 1. An asphaltum photographic process, consisting in combining a selected asphaltum with a colloidal halide, subjecting the same to a luminous image, and in subsequently developing the print by means of a suitable solvent to remove variable soluble parts of the impressed image.

2. A resinous photographic process which comprises combining a slightly sensitive natural resin as the main base of a photographic medium with a small percentage of a halogen-liberating sensitizer, subjecting the sensitized medium to a source of illumination, and subsequently developing the same by means of a suitable solvent.

3. A photographic process, consisting in combining an asphaltum'with a solvent, in adding thereto a halogen liberating agent and a suitable solvent, in coating a surface therewith, in subjecting the coated surface to a luminous image, in developing the image and in 'finally rinsing the same.

4. A rapid photographic process, consisting in using a slightly sensltive asphaltum with a solvent, in adding a sensitizer and solvent which is non-reacting on the asphaltum in the dark but which forms an actinic medium highly sensitive to light, in subjecting a coating of such medium to a luminous image, and ln-subsequently developing the same.

5. A photographic process consisting in combining solvents with a natural resin taken as the main base of a photographic medium, sensitizing the solution by com-. bining therewith an iodine compound and a solvent yielding a stable mixture which will not deteriorate in the dark, printing by means of a variably luminous image on a surface coated with said mixture, and

develo ing the print.

6. e process of producing an actinic sensitizer for natural resins, which com. -pr1ses combining iodoform, ethyl methyl ketone, a suitable solvent, and a traceof concentrated ammonium hydroxide.

7. The process of producing an actinically sensitive coating which comprises 'combin-- ing with asphaltum a colloidal halide in the presence of co-operating solvents.

8, A photographic process comprising forming a light-sensitive medium of a natural resin employed as the main base of a photographic medium by sensitizing the same with a halogen-liberating agent to form a stable mixture, applying a coating of said mixture to a grained metallic plate, exposing the coating to a luminous image, and developing with a, suitable solvent.

9. A process of producing a stable, lightsensitivemedium which comprises incorporating in a natural resinsuch as asphaltums, bitumens, asphaltites, etc., taken as the main base of the medium, and a solvent, a halogen-liberating compound which remains stable in such medium during storage.

10. The process of producing an actin ically sensitive medium which comprises mixing to ether 10% asphaltum, 40% solvent napht a, and 25%benzine; and incorporating therewith a solution comprising a halogen compound, such solution constitut- 7 ing approximately 25% of the sensitized medium.

11. A photographic medium consisting of approximately the following: 75% asphaltum solution, 25% sensitizing medium consisting of approximately 34% iodoform'and ethyl methyl ketone and 66% solvent.

g 12. A photographic medium,' comprising a natural resinous compound as a main base, and a halogen-liberating sensitizer incorporated therein.

13. A photographic medium, comprising a slightly sensitive natural resinous compound as a main base, and a sensitizer incorporated therein comprising a light-sensitive metallic halide.

14. A photographic medium,- comprising a slightly sensitive natural resinous c0mpound as a main base, and a sensitizer incorporated therein comprising alight sensitive colloidal metalliclhalide and a .halogen-liberating organic compound.

15. A photographic medium, comprising a slightly sensitive natural resinous com pound as a main base, and asensitizer incorporated therein comprising a light-sensitive metallic halide. and iodoform.

16. A photographic medium, comprising a selected light-sensitive asphaltum, and a ,a halogen-liberating compound.

17. A photographic medium, comprising a 'selected light-sensitive asphaltum, and a sensitizer incorporated therein comprising a light-sensitive metallic halide and a halogen-liberating organic: compound."

18. A "photographic medium, comprising a selected light-sensitive asphaltum, and a sensitizer incorporated therein comprising a light-sensitive metallic halide and iodoform. p

19. A photographic medium, comprising a selected light-sensitive asphaltum and a sensitizer incorporated therein comprising iodoform.

In testimony tures.

' MURRAY 0. BEEBE.

ALEXANDER MURRAY.

whereof we afix our signa- 

